Influence of different atmospheres on the thermal decomposition of Al-Cr-N coatings

Metastable cubic (c) AlCrN coatings decompose during thermal annealing into their stable phases Cr and hexagonal (h) AlN under the release of N 2 . We show that the onset temperature T o and amount of N 2 release depend on the ambient atmosphere. For c-Al 0.56 Cr 0.44 N only a partial dissociation into h-AlN and h-Cr 2 N with T o ∼ 1180 °C occurs during annealing in N 2 up to 1450 °C. Experiments in synthetic air to 1450 °C yield a complete oxidation to (Al 0.56 Cr 0.44 ) 2 O 3 .